I’m the annoying guy in your office that likes to pull little pranks on other people in the cubicle farm. I go for small scale stuff though, lower your chair, unplug your keyboard, draw something on your notepad 20 pages in. One of my favorite harmless ones was when I took a photo of a coworker’s desk and then made that her desktop image. I then took another photo (with the computer right in the center) and made that her desktop image. I repeated it another bunch of times until the recursive image was small enough to resemble reaching into infinity.

I pulled a little prank on a friend in school once. I had programmed a fake dialog box in beforehand (not as tricky as it might sound) and saved it on my flash drive. As soon as my friend left his computer for a short while (without logging out), I copied the dialog box to his computer via my flash drive and opened it.

It was a series of dialog boxes that kept on asking him the same annoying question over and over again, and the only available answers were yes and no, the X in the corner was grey and unclickable! …But it didn’t loop infinately, ’cause I’m not *that* mean!

Or tell them you have shrapnel in your skull. Same thing.
One of the most evil things I’ve done is to get one of those musical cards, remove the noisemaker, short out the switch so it plays all of the time, insulate it with tape, and shove it through the vents of a co-workers CRT monitor.

Every year, the last day of school is Senior prank day. The year before i graduated, we were all very disapointed in the seniors who did things like cover a whiteboard in my little pony stickers and moving the furniture in the break hallway into various other parts of the school. When I made it senior year i picked one class room (the one with the teacher who had a sense of humor) and grabbed my best friend and several packs of sticky notes. we spent the day before counting everything in the class and labeling the sticky notes, then on the last day, we covered his room. the best part was we did it during class and he didn’t notice a thing. I went behind his desk where he was sitting and labled his pet spider tank and all of his files. i reached over his shoulder and stuck a not to his computer screen labled ‘computer’. when we were done and the rest of the class was trying not to laugh we sat down and someone raised their hand and asked ‘did you feed the spider today? she’s freakin out.” he turned around and saw a little note labled ‘hairy monster’. then he looked around and saw his entire classroom covered in post-its. i came back a few days later b/c i had to pick my brother up. before i even got to his class i heard ‘theres /another/ one!!” He had yet to find the one i put on the emergancy exit door labled ‘Narnia.’ My cousin one uped me though. he and his friends disassembled a car and reassembled it (Minus engine and some heaver parts) in the lunch room.